1. Field of the Invention
The present invention pertains to a process for securing products against forgery with a machine-readable security feature.
2. Description of the Related Art
In particular, personal documents, banknotes, securities, documents, service cards, such as credit cards or the like, postage stamps, but also other products, such as drugs, spare parts, jewels, generally products that have an economic significance or must be authorized, often can be prepared according to a process that can be easily imitated.
It is desirable in the case of these products to introduce features that make it possible to prove their authenticity, i.e., their originality.
The security features should be connected to the product to be authorized possibly inseparably and/or possess properties that are difficult to reproduce.
The preparation and the use of security features in products belong to the general state of the art.
The machine-readable security features are of particular significance.
Special inks with spectral peculiarities or with magnetic properties or with temperature dependencies (thermochromic inks) are frequently introduced as a security feature into the product to be protected. Bar codes are used, in which the differences in the reflectivity of the surface are utilized, and grid structures or even foil antennas are used to utilize the resonance frequency in a resonant circuit.
The common feature of the prior-art machine-readable security features is that even though they differ in terms of the degree of security against forgery, they can generally be reproduced by varying efforts and very often they can be made optically visible and thus they do not offer sufficient security against forgery.